A Study On The Control System Of The Electronically Controlled Air Suspension Of An Advanced Passenger Vehicle

Air suspension is an important direction for the development of vehicle suspension systems.At present,air suspensions are widely used in various passenger vehicles and commercial vehicles in developed countries around the world,and their electronic control is getting higher and higher,and the technology is becoming more and more mature,which is called electronically controlled air suspension(ECAS).The vehicle air suspension system of China is currently in an important stage of development and upgrading,and ECAS technology is also in research and development.Therefore,it is of great significance to study the ECAS control system.This paper takes a high-class passenger car as the research object,and uses the ECAS technology for the car to carry out the following research work:(1)According to the various sports modes of the car,the ECAS control system structure was designed,and the key components such as sensors and air spring/hydraulic damper module were selected,and the ECAS control system development task summary table was formulated.(2)The vehicle dynamics mathematical model and Simulink simulation model controlled by ECAS were established,and various standard pavement and discrete pavement models were established and used as input for vehicle simulation.The constructed vehicle dynamics and control simulation system provides a platform for the study of ECAS control algorithms.(3)Based on the constructed vehicle dynamics and control simulation platform,the ECAS vehicle height adjustment control,straight-line ride comfort control and body level control research were carried out: the Fuzzy-PID controller is designed to control the vehicle height adjustment process when the car is stationary and in operation,which obviously avoids the problem of “overcharge” and “over-discharge” of the air spring,and also makes the vehicle height adjustment stable,fast,and the error is very small;when the car is driving in a straight line,a fuzzy control algorithm for switching the damping position of the damper is developed based on the vehicle response knowledge base,which effectively reduces the resonance of the unsprung mass and improves the ride comfort of the car;when the car is tilted due to steering,acceleration or braking,the damper damping switching control and the air-filled Fuzzy-PID control of part of the air spring are used to quickly and effectively keep the vehicle body in a horizontal stable state.The research on the structure design of ECAS control system,the c onstruction of vehicle dynamics,control simulation platform and the intelligent control algorithm are the basis for the next step of ECAS system engineering development.